Machine for the automatic reproduction of prints using a photosensitive process



Nov. 5, 1968 e. MATTHAES 3,409,363 MACHINE FOR THE AUTOMATICREPRODUCTION OF PRINTS USING A PHOTOSENSITIVE PROCESS Filed March 9,1965 2 Sheets-Sheet 1 h h W 22 J GOTTFR/ED MAT THAE$ INVENTOR.

Nov. 5, 1968 G. MATTHAES MACHINE FOR THE AUTOMATIC REPRODUCTION OF PRINUSING A PHOTOSENSITIVE PROCESS Filed March 9, 1965 2 Sheets-Sheet 2INVENTOR. GOTTFR/ED MATT/MES United States Patent ABSTRACT OF THEDISCLOSURE A machine for automatically reproducing prints using aphotosensitive process employing an upright member having radiallyextending arms which rotate about the upright member as well as movevertically. A plurality of work stations are arranged radially aroundthe upright member and include a coating station and first and secondphotographing stations where a plate is suspended from one of the arms.At this location the plate is lowered to the coating station to becoated with a photosensitive substance and then lowered into the firstand second photographing stations to have both faces printed.

The present invention pertains to the formation of an image on a plainmetallic surface and more particularly to the formation of such imagesfor use in producing printed circuit plates.

The image must be resistant to acids in order to ensure the protectionof a portion of the metal during the chemical etching producing thedesired image.

Several methods for the formation of such images are known, such as silkscreen printing, off-set processing and photosensitive printing. Thelatter method has the advantage of a more clear and precisereproduction; however, photosensitive printing has previously beenperformed by hand, and involves the following operations:

Cleaning of the metallic surface;

Applying a photosensitive coating on the cleaned lic surface;

Drying the photosensitive coating;

Sensitizing the photosensitive coating my means of a photographicnegative and ultraviolet light;

Developing the unsensitized portion of the coating;

"- Coloring the coating for greater visibility; and

Water washing and drying.

Although the precision obtained by photosensitive printing is great, ithas not been utilized to any great extent beo ause of the expenditure ofworkmanship necessary to perform the aforesaid operations.

Attempts have been made to construct an automatic machine-capable offulfilling the above operations on a single transportation line throughindividual working stations; however, these machines have not enjoyedany favorable success due to their systems of transportation, and theirinability to obtain the formation of the image for precise reproductionwithin the restricted tolerances, which is the advantage ofphotosensitive printing.

Accordingly, it is an object of the present invention to construct amachine for automatically reproducing prints using a photosensitiveprocess by utilizing a roundabout structure.

Another object of the present invention is to construct a machine forautomatically reproducing prints using a photosensitive process in theform. of a roundabout having rigid, radially disposed supporting arms,each one of which supports a suspending device to receive the plates tobe printed.

One important feature of the present invention is that the suspendingdevice, in cooperation with guide means metal- 'ice on a photographicchamber, ensurses the precise position if the plates to be printedwithin the photographic cham- The suspending device further serves toease loading and unloading operations, which can be performed by anoperator standing beyond the circle defined by the radially disposedarms of the roundabout.

Another important feature of the present invention is the provision ofmeans for the regulation and control of the position of glass plates, onwhich photographic negatives are fixed, to ensure the coincidence of theposition of the photographic negatives with the image desired on theplate to be printed.

Another feature of the present invention is the provision of apparatusfor applying a photosensitive coating on the plate to be printed, so asto obtain a photosensitivepoating of'thin and uniform thickness which isrequired for good quality reproduction.

Other objects and advanages of the present invention will becomeapparent from the following description of a preferred embodiment of thepresent invention as shown in the drawings in which:

FIG.'1 is a top view of a machine according to the present invention;

FIG. 2 is a side view of parts of the machine of FIG. 1;

FIG. 3 is a side view of a suspending device for use in the presentinvention and i FIG. 4 is a schematic view of apparatus for ensuring theexact positioning of the plate to be printed.

The present invention is constructed in the form of a roundabout with,for instance, eight radial arms B which rotate around a central uprightC. These arms may be lowered to vessels situated underneath the arms.Working stations are arranged beneath the arms radially around centralupright C. The number of treatment vessels may be greater than,less'than or equal to the number of radial arms B. In FIG. 1 there areshown the following stations of treatment:

1unloading the printed plates 2-loading the plates to be printed3cleaning the plates to be printed 4coating the plate withphotosensitive substance 5--drying by infrared rays 6-cooling 7-firstphotocamera 8--second photocamera 9-developing the plates 10-coloringthe plates 11-washing the plates 12drying the plates.

, As pointed out above, an important feature of the present invention isthe device for suspending the plates, the purpose of which is toprecisely dispose the plates within the photographic cameras in order toensure the exact positioning of the plates to be printed with respect tothe glass plates bearing the negatives.

The suspending device is illustrated in FIG. 3, and comprises asupporting plate 13 suspended from the radial arm B by means of twolateral springs 14-14 and a central pivot 15 engaged in 16. The positionof supporting plate 13 is adjustable vertically by means of a screw 17and horizontally by means of a screw 18.

Further, the suspending device cooperates with photographic cameras 7and 8, to exactly position the plates by means of two operating surfaces19-19 which rest on two prisms 2040 on the cameras. Springs 14-14together with pivot 15 allow supporting plate 13 to be set in an exacthorizontal position during while resting of surface 19-19', on prisms20-20.

The plates to be printed are suspended on supporting plates 13 by meansof a strip 21, which is provided with hooks 22 for suspending plates Lto be printed. Strip 21 is introduced into and drawn back laterally onsupporting plate 13 so that the loading and unloading of the plates tobe printed may be performed by the operator while remaining outside thecircle formed by radially disposed arms B of the roundabout.

. A thin, uniform coat of photosensitive substance or photoresist isapplied to plate L at the station 4 which includes a vessel 33, intowhich the plate to be printed is in. troduced as shown in FIG. 2. Afterthis introduction, an electrically driven pump 35 fills the vessel withphotoresist until the plate to be printed is submerged. At this time,the pump 35 is stopped and a discharge valve 36 is opened to allow thephotoresist to flow into a tank 38 lodged beneath the vessel. Theviscosity of the coating substance and its fast discharge into tank 38determine the desired thickness of the coating on the plate to beprinted, and this thickness is controllable at will.

The photoresist must be absolutely free from dust and solid particlessince their presence wouldcause imperfections in the print, and themachine of the present invention is therefore equipped with aphotosensitive coating station wherein the plates are dipped into avessel which is then filled with photoresist. After the photoresist hasreached a predetermined level, a variable valve is opened, and theresist exits slowly into a tank below the vessel. The surface tension ofthe photoresist will leave a thin film on the plate and droplets will bedrawn away.

Design of the valve and shape of the vessel may be chosen so that theexit speed of the liquid is such that the layer of the resist is equalat any level of the plate.

The resist should exit quickly at the beginning and slower when thelevel of the resist has reached the lower part of the plate where athicker layer has been formed by the retreating resist on the plate.

While flowing to the main tank the resist passes a filter where allimpurities are eliminated, and a perfect print without pinholes can beachieved.

After the plates have left the coating station, the pump or similardevices transport the resist back to the container to coat the nextplate. An exact control system and a large overflow insure accuratemaintenance of the resist level.

Dipcoating of the plates applies a layer of resist on both sides so thatthe plates can be printed in two successive photoprinting stations.

Within the photographic cameras 7 and 8, one of which serves to printone face of the plate L and the other one to print the opposite face ofthe same plate, glass plates 34 bearing negatives 24 to be reproducedonto plates L are contained as shown in FIG. 4.

Within each of cameras 7 and 8 apparatus is provided to ensure'theprecise positioning of the plate L to be printed with respect to glassplate 31 bearing the nega tive 24. This apparatus is illustrated in FIG.4 and comprises a frame 26, whereon a flexible sheet 23 is fixed, made,for instance, of rubber. Frame 26 also has pivots or pins 27 attachedthereto, and rubber sheet 23 has a mouth 32 communicating with a vacuumpump 33 and a mouth communicating with a contact vacuum meter 29. Theplate to be printed is indicated at 30 in FIG. 4. An electric switch 25is connected in series between a source of electricity 40 and vacuumpump 33, and source 40 is also connected in series between actinic lamps28 and vacuum meter 29.

The operation of the apparatus is such that after plate 30 has beenlowered into one of the cameras 7 or 8, frame 26 and glass plate 31 aredisplaced in the directions indicated by the arrows by any conventionalmeans, not shown. Pin 27 will pass through holes in-the plates 30 and 31in order to precisely position the plates With respect to each other.When pins 27 have passed through the holes of both plates, electricswitch 25 closes which starts vacuum pump 33. Due to the vacuum withinthe photographic chamber formed by frame 26, sheet 23 and plate 31,plate 30 is pressed against glass plate 31.

For precision printing and reproducing the position of plate 30 withrespect to negative 24 on glass plate 31, it is necessary that pins 27,provided for reference purposes, allow plate 30 liberty of movement. Tothis end, pins 27 close electric switch 25 to start vacuum pump 33 onlywhen both plates have assumed their exact position, in other words, whenthe pins have traversed both plates.

It is also important that lamps 28 do not light the plates before theyare pressed against one another in good order. To this end, a contactvacuum meter 29 is provided, which closes a switch to permit lighting oflamps 28 only when the vacuum within the photographic chamber'issufficient to ensure the indispensable contacting o-fboth plates.

The other working stations of the roundabout are known and do notrequire particular description.

Since the present invention is subject to many variations, modificationsand changes in detail, it is intended that all matter contained in thespecification or shown on the drawings shall be interpreted asillustrative and not in a limiting sense.

What I claim is:

1. In a machine for the automatic reproduction of prints using aphotosensitive process and constructed in the form of a roundabout, thecombination comprising an upright member, a plurality of arms radiallydisposed from said upright member, means connecting said plurality ofarms with said upright member so that said arms are rotatable about saidupright member and vertically movable, a plurality of working stationslocated beneath said arms and radially around said upright member, and aplurality of suspending means each attached to one of said plurality ofarms and adapted to support a plate to be printed and each of saidplurality of suspending means including a supporting plate, horizontaladjusting means connected with said supporting plate, and verticaladjusting means including a central pivot connected with said supportingplate.

2. The invention as recited in claim 1 wherein each of said plurality ofsuspending means includes a strip attached to said supporting platehaving hooks suspended therefrom to hold the plate to be printed.

3. The invention as recited in claim 1 wherein one of said plurality ofworking stations is for coating the plates to be printed with aphotosensitive substance and includes a vessel, a tank disposed beneathsaid vessel, a pump for transferring the photosensitive substance fromsaid tank to said vessel and valve means for draining the photosensitivesubstance into said tank from said vessel Whereby a plate to be printedmay be coated by lowering its associated arm and suspending means to dipthe plate into the vessel and then withdrawing the plate.

4. The invention as recited in claim 1 wherein said plurality of workingstations includes a first photographic means for printing'one face ofthe plate to be printed and a second photographic means for printinganother face of the plate to be printed.

5. The invention as recited in claim 1 wherein said plurality of workingstations includes photographic means having a glass plate with referenceholes therein adapted to have a negative aflixed thereto, a frame withreference pins thereon, and a flexible material attached to said framewhereby the insertion of the reference pins of said frame throughreference holes in the plate to be printed and the reference holes insaid glass plate assure the exact positioning of the plate to be printedwith respect to said glass plate.

6. The invention as recited in claim 5 wherein said photographic meansincludes a vacuum pump and said flexible material has a mouth connectedto said vacuum pump whereby said pump is energized after said referencepins have been inserted through the reference holes 5 6 in said glassplate to secure the position of the plate to References Cited beprinted.

7. The invention as recited in claim 6 wherein said UNITED SFFATESPATENTS photographic means includes lighting means, vacuum 3,319,5565/1967 Flore 9573 sensing means connected with said flexible materialand 5 FOREIGN PATENTS means connecting said lighting means With saidvacuum sensing means whereby said lighting means is energized 121184/1933 Austraha' after said vacuum sensing means senses a suflicientvacu- NORTON ANSHER Primary Emmi-"en um to assure that the plate beprinted is firmly pressed against the glass plate. R. A. WINTERCORN,Assistant Examiner.

